The invention relates to a vibration device for displacing a mass into a one-dimensional, reciprocating, forced movement, comprising a device for compensating the inertia force generated by the mass, which mass includes at least one pair of equally large compensating masses which, themselves or in cooperation with regard to their effective position, are changeable in position and rotatable in the opposing direction of rotation with respect to one another in such a manner that their centers of inertia, at the point in time of reversal of the mass, point in the direction with respect to the rotational axis opposite to the inertia force to be compensated at this point in time, their eccentricity and their mass being dimensioned such that their centrifugal forces effective during the rotation essentially compensate the inertia forces emanating from the one-dimensional reciprocating mass, the compensating masses respectively being arranged on coaxial shafts driven in opposite directions of rotation, one of the shafts being a hollow shaft by means of which the mass is moved via an eccentric device.
Such a vibration device is known from DE-PS 37 27 742 and is used, for example, for vibrating heavy cylinders of a paper machine in order to increase by means of the vibration the dewatering and quality of the resulting paper sheeet. The vibrational movement is effected in a horizontal direction, a one-dimensional movement transverse to the direction of movement being generated with two reversal points on account of the unvariable length of the paper machine screen. The vibration of the large mass of the cylinders in their axial, i.e. horizontal direction causes correspondingly large vibrations during the constant reciprocating acceleration and braking of the mass, which vibrations must be absorbed by the base of the machine via the structure of the machine. This effects and loads the entire building in which the machine is erected. By means of such a vibration device, the forces arising during the vibration are almost completely compensated for.
The compensating masses consist of partial masses which are located on disks rotating with the shafts, the disks being movable relative to one another along a circular path by means of a displacing mechanism. The center of inertia of the compensating masses ensuing on account of the displacement can therefore be adjusted, i.e. the eccentricity of the compensating masses to the rotating axis. The displacing mechanism serves to simultaneously displace the center of inertia of the compensating masses to a position which is advantageous for the set stroke of the vibrationary movement.
From DE-OS 27 38 794 a vibrator is known which is equipped with two coaxial shafts. Of these coaxial shafts, one is a hollow shaft. Coaxial shafts are adjustable with respect to one another by means of special devices.
It is an object of the invention to provide such a vibration device which particularly in view of the displacement of the inertia force compensating system, is constructed in such a way as to enable a displacement which is as simple as possible. Additionally, a compact structure is to be realized in accordance with the invention.